When the waveform data of a biological signal, such as an electrocardiographic signal, is compressed, the waveform of the biological signal may significantly deteriorate and affect medical decision. Therefore, usually, the compression processing is not performed on the biological signal. However, recently, there are also increased opportunities for remote medical care and storage of biological information, and various kinds of techniques also have been proposed, which compress a biological signal using an audio compression technique and output the compressed biological information to an external terminal or memory (e.g., see Patent Literatures 1, 2).
Patent Literature 1 proposes a medical terminal device that compresses the electrocardiographic data converted to digital data and outputs the compressed electrocardiographic data to a device on the doctor side via a telephone line. Patent Literature 2 proposes a Holter monitor device that compresses digital-converted electrocardiographic data using a wavelet code transformation method and stores the compressed electrocardiographic data into an external nonvolatile memory.